1. Field of the Invention
The present invention relates to a terminal fitting that can be crimped into connection with a wire.
2. Description of the Related Art
A terminal fitting that can be crimped into connection with a wire is disclosed in Japanese Unexamined Patent Publication No. 4-209471, and is identified generally by the numeral 100 in FIGS. 9 to 13 of this application. The terminal fitting 100 has a barrel-type wire-fastening portion 101 with a bottom wall 102 and first and second fastening pieces 103, 104 that extend upward from the left and right side edges of the bottom wall 102.
An automated apparatus is used to crimp the wire-fastening portion 101 into connection with a wire 105. First, as shown in FIG. 9, the wire-fastening portion 101 is placed on an anvil 106 and the wire 105 is placed between the two fastening pieces 103, 104. A crimper 107 is located above the anvil 106 and is provided with an arch-shaped guide surface 108 formed with a stepped stopper 109 substantially at the uppermost position. The crimper 107 then is lowered to crimp the fastening pieces 103, 104 to the wire 105.
During the lowering process, a leading end 103A of the first crimping piece 103 contacts the stopper 109 and is held tense, and a leading end 104A of the second crimping piece 104 contacts the leading end 103A of the first crimping piece 103 and is held tense (see FIG. 10).
Thereafter, the leading ends 103A, 104A of the first and second crimping pieces 103, 104 are bent inwardly. More particularly, the first crimping piece 103 departs from the stopper 109 and is bent along the guide surface 108 with a decreasing radius of curvature. Simultaneously, the second crimping piece 104 is bent along the inner side surface of the first crimping piece 103 with a decreasing radius of curvature. As a result, the first and second crimping pieces 103, 104 are crimped and fastened to the outer circumferential surface of the wire 105.
The crimping of the terminal fitting 100 may cause the leading end 104A of the second crimping piece 104 to be bent away from the intended bending direction, as shown in FIGS. 11 and 12, and into a reverse fold, as shown in FIG. 13. If this occurs, the folded leading end 104A may be broken along the fold and may come out through a clearance between the first crimping piece 103 and the wire 105. As a result, a clearance may be formed between the first crimping piece 103 and the wire 105, and a reduced fastening force may result.
The above-described problem is particularly prominent in terminal fittings in which a projection 110 is formed on the inner side surface of the second crimping piece 104 for strengthening a fastening force so that the projection 110 bites in the outer circumferential surface of the wire 105.
In view of the above problem, an object of the present invention is to securely crimp crimping pieces into connection with a wire.
The subject invention is directed to a terminal fitting that comprises a wire-fastening portion with a bottom wall and at least first and second crimping pieces that extend from the bottom wall. The wire-fastening portion can be crimped into connection with a wire such that the second crimping piece is deformed to reduce a radius of curvature while moving substantially along the inner side surface of the first crimping piece. Thus, the first and second crimping pieces substantially surround the outer circumferential surface of the wire.
The second crimping piece is recessed to form a deformation-facilitating portion or a weakened portion that facilitates a bending or deformation that inclines a leading end portion of the second crimping piece inwardly. Accordingly, a crimping error that deforms the leading edge in a direction opposite from an intended direction can be prevented.
Preferably, the second crimping piece is formed with a projection on the inner side surface. The projection is dimensioned and configured to bite into the outer circumferential surface of the wire. The deformation-facilitating portion preferably is formed between the projection and the leading end of the second crimping piece. Accordingly, the second crimping piece is bent between the leading edge and the projection to incline the leading edge inwardly. Angles of inclination of the bent leading end with respect to a guide surface and the first crimping piece are small as compared to a case where the second crimping piece is bent between the bottom wall and the upper projection. Thus, the second crimping piece is moved smoothly along the inner side surface of the first crimping piece to reduce a diameter.
The deformation-facilitating portion may comprise a groove that extends along at least one side surface of the second crimping piece, and preferably along the inner side surface of the second crimping piece. Additionally, the groove preferably is aligned substantially normal to the extension of the second crimping piece. Thus the groove lies substantially along a bending line, and bending can be performed more securely.
The leading end of the second crimping piece is bent about a point on the outer side surface of the second crimping piece that substantially aligns with the deformation-facilitating portion. Additionally, the groove is open in the inner side surface. Accordingly, there is no likelihood that the opening edge of the groove will be caught by the inner side surface of the first crimping piece and the guide surface while the second crimping piece is deformed to a reduced diameter during the crimping process.
The deformation-facilitating portion may be formed by thinning the second crimping piece, such as by stretching the metal plate used to produce the terminal fitting.
The bottom wall may be formed with at least one bottom projection for contacting and biting into the wire.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings.